Thanks for that. It appears that the Channel-billed Cuckoos are more sociable than other cuckoos and they do it seems sometimes migrate in small groups. Plus
sometimes multiple laying could likely make a big difference in behaviour. There is room for consideration that there is still active evolution and change going on in the whole dynamics of this parasitic behaviour. As shown by the range of strategies the host
species try to use to avoid and the range of strategies the parasites use. Several other bird groups are parasitic and some cuckoos are not parasitic (the coucals and the malkohas in Asia).
From: Dr David Rosalky [
Sent: Monday, 13 January, 2025 9:49 AM
To: 'Philip Veerman'; 'shorty'
Cc: 'CanberraBirds email list'
Subject: RE: [Canberrabirds] More on the Koel
Hi Philip
I thought this was a very plausible analysis. I have two comments:
- When I observed my first Channel-billed Cuckoo with foster parents, there were two chicks in a magpie nest (I still feel sorry for the magpies). I
just happened to have been there when the young fledged. But there was an adult nearby calling. I reported to this group and I recall that someone said there was evidence of association amongst CBCs. I note that HANZAB makes no mention of association but
good information on multiple laying in host nests.
- Speaking of HANZAB, there is some suggestive text that there may be association amongst Koels. In the section “Relations within family group” (vol
4, p765), there are two references to adults perching nearby for some days after the young hatched. As I say, only suggestive but nonetheless intriguing.
David Rosalky
From: Canberrabirds <>
On Behalf Of Philip Veerman via Canberrabirds
Sent: Sunday, 12 January 2025 10:09 PM
To: 'shorty' <>
Cc: 'CanberraBirds email list' <>
Subject: Re: [Canberrabirds] More on the Koel
Sorry but I suspect, to take this further can only be a bit tedious and repetitive (apologies, I find it so, but here goes anyway). Because these are nest parasites,
there is no actual reason to think that there should be any interaction between adult cuckoos and young ones. I can’t think of any good reason why there would be. It is obviously not required, as the young Koels clearly are capable of making it on their own,
without any assistance of adults. Being not required in every case, it won’t be in their instincts to have such a behaviour. Because it is a complex set of behaviours to come about. It is may be possible, but very unlikely, that the adults, especially adult
males, can have any way of knowing who is their direct offspring. So why evolve a counter intuitive behaviour? For what it is worth, many migratory birds have adults leave the nest area earlier and separate from the young birds.
So I suggest, in terms of scientific method, the null hypothesis has to be that there is no social connection between the Koel adult and chicks. The null hypothesis
does not need to be proven (although can be disproven). The alternate hypothesis (thus available to demonstrate) is that there is a social connection there. That there is so little (if any) evidence that there ever is, does not make it overly useful to search
for reasons why there should be. The observations reported are (I suggest) simply that of coincidental proximity. As the species has become quite common here, proximity is bound to happen. Our Canberra environment seems to be a special case, the birds that
arrive here seem to stay for the whole summer (don’t move on), as they are not very often found outside of the Canberra region. This is probably because of food. So the adults are sort of stuck here while the kids grow up. That is probably why the occasionally
seen proximity of adults and juveniles happens here. But no substantial connection has been shown. If it was important it would be noticed a lot. However, that this proximity happens infrequently enough to be thought interesting to comment on, is of itself
supportive of that it is not of significance and is likely to be simply coincidental. Given that the normal situation of a parasite is to have no contact, as normally the parents would have long moved away, if it was important (or even useful) to have this
contact, for example for adults to (amazingly) find their own young and guide them on migration, then the behaviours to facilitate something so very difficult, would clearly need to be very highly developed. It clearly is not.
I am not suggesting I know whether the answer to this is yes or no (or if anyone does). But I think there is nothing to see here. Just that there should be
a better start point to clarify if there is a basis for a question and then if there is, what direction to approach the question from. .
Philip
